Space heater for enclosed substation - has its operation controlled by dew point detectors with peltier element in coolest part of substation

摘要

The purpose of the circuit is to save energy by switching off the heater when there is no danger of moisture condensing out onto the insulator surfaces in a substation. A heater (8) is under the control of a dew point sensor (9) whose detecting element is subjected to more intense cooling than the rest of the installation. In consequence moisture is condensed on the detector before the dew point for the rest of the enclosure is reached. The equipment is thus safeguarded as the heaters will be on in time to prevent condensation. When the dew point is below the detector temperature the heaters are again switched off. Peltier elements may be used as detectors and their output, suitably amplified, is used to operate the relay switching the heater.